In one aspect, the present invention is directed toward a method for filtering various materials with a porous filter media prepared from a random fiber composite sheet.
It is desirable to prepare filters or membrane supports having good physical strength and varying porosity. This is, however, difficult with most of the known methods for preparing filters and filter materials. Examples of known filters are sintered glass, fritted metal, woven or leached polyolefins and paper.
Polymeric composites containing reinforcement means are known in the art and methods for their preparation are disclosed in U.S. Pat. No. 4,426,470. Generally, this method employs an aqueous wet-laid technique to prepare a composite comprising a thermoformable polymer, reinforcing fibers and a binder such as latex. The composite so prepared exhibits good physical properties having a combination of high flexural strength and compaction resistance. Also, the composite can be molded into a variety of shapes. It has now been discovered that such composites can be controllably lofted into porous materials to yield a wide range of porosity, particularly adaptable for filter media and membrane supports.